Prevalence of pernicious anaemia in patients with Type 1 diabetes mellitus and autoimmune thyroid disease.

AIMS: To determine the prevalence of pernicious anaemia in patients with Type 1 diabetes mellitus and autoimmune thyroid disease. METHODS: A randomly selected asymptomatic group of 63 patients with Type 1 diabetes who also had autoimmune thyroid disease was studied. Blood samples were taken and assayed for serum B12. Those subjects with serum B12 concentrations below the reference range had a further blood sample taken for determination of intrinsic factor antibody. RESULTS: One patient had been diagnosed previously to have pernicious anaemia. Three patients had low serum B12 concentration and positive intrinsic factor antibody, confirming the diagnosis of pernicious anaemia. The prevalence of pernicious anaemia in this population with Type 1 diabetes and concomitant autoimmune thyroid disease was 6.3%. In female patients the prevalence of pernicious anaemia was 8.5%. CONCLUSIONS: Patients who have both Type 1 diabetes mellitus and autoimmune thyroid disease are at risk of developing pernicious anaemia.